Cell site power generation

ABSTRACT

A system, apparatus, method, and manufacture for generating backup power in a wireless communications system such as a wireless communications service base station. The system includes a communications interface, a primary power interface, a generator, rectifiers, and a battery circuit. During normal operation, the communications interface is powered from the primary power interface. During a power outage, the communications interface is powered from either the generator or the battery circuit. The generator is cycled on and off during power outages to charge the battery circuit while conserving fuel. To decrease rectification loss, rectifiers are run near full load while rectifying the generator output.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/202,507, filed on Jul. 5, 2016, and entitled “CELL SITEPOWER GENERATION;” which is a divisional application of U.S. patentapplication Ser. No. 14/251,539, filed on Apr. 11, 2014, and entitled“CELL SITE POWER GENERATION,” now U.S. Pat. No. 9,386,518; which is adivisional application of U.S. patent application Ser. No. 12/170,675,filed on Jul. 10, 2008, and entitled “CELL SITE POWER GENERATION,” nowU.S. Pat. No. 8,729,732; all of which are hereby incorporated herein intheir entireties by reference. This application is also related to U.S.patent application Ser. No. 12/365,165 filed Feb. 3, 2014, now U.S. Pat.No. 8,279,074, and entitled “BATTERY MONITORING SYSTEM, SUCH AS FOR USEIN MONITORING CELL SITE POWER SYSTEMS”, which is incorporated byreference herein in its entirety.

BACKGROUND

The popularity of commercial wireless communications services (e.g.,wireless telephony, wireless network access, and wireless email) hassubstantially increased during recent years. In many cases, users, suchas consumers, mobile workers, emergency response personnel, and/or thelike, now utilize these services for both personal and businesscommunications. Likewise, users are also increasingly relying on theseservices. For example, some households forgo wired telephone service infavor of wireless telephone service, some government agencies rely onthese services for both routine and emergency communications, andbusinesses rely on these services to communicate with customers andmobile workers. Correspondingly, the cost (both financial andnonfinancial) of outages is also increasing.

Typical commercial wireless communications service (CMRS) providers relyon remote facilities to facilitate the provision of services. Forinstance, CMRS providers rely on base stations (e.g., cell sites, radiorepeaters, wireless to backhaul interfaces, etc.) to facilitate somecommunications services. If a base station experiences a loss ofcommercially-provided electrical power, users near the base station mayexperience a service outage. Power outages are an example of a commoncause for base station failures. For example, natural disasters, rollingbrownouts, accidents, and/or the like may result in power outages. Whilemost base stations include some form of backup power (e.g., generatorsand/or batteries), these forms of backup power may not providesufficient power during lengthy power outages and may require servicing,monitoring, and on-site maintenance. During lengthy power outages, useof commercial wireless communications services may increase due tousers' needs and/or desires. Further, pending regulations may requirecommercial wireless communications service providers to provide basestations with at least seven days of backup power.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of an environment forpracticing the invention;

FIG. 2A is a block diagram of a base station in accordance with anembodiment of the invention;

FIG. 2B is a block diagram of components of a rectifier and switchcircuit in accordance with embodiments of the invention;

FIG. 3 is a block diagram of a power controller usable in the basestation of FIG. 2A in accordance with an embodiment of the invention;

FIG. 4 is a schematic diagram of a battery circuit usable in the basestation of FIG. 2A in accordance with an embodiment of the invention;

FIG. 5 is a schematic diagram of an opto-isolator usable in the batterycircuit of FIG. 4 in accordance with an embodiment of the invention; and

FIG. 6 is a logical flow diagram of a process for conserving power in awireless communications system in accordance with an embodiment of theinvention.

DETAILED DESCRIPTION

The following description provides specific details for a thoroughunderstanding of, and enabling description for, various embodiments ofthe technology. One skilled in the art will understand that thetechnology may be practiced without many of these details. In someinstances, well-known structures and functions have not been shown ordescribed in detail to avoid unnecessarily obscuring the description ofthe embodiments of the technology. It is intended that the terminologyused in the description presented below be interpreted in its broadestreasonable manner, even though it is being used in conjunction with adetailed description of certain embodiments of the technology. Althoughcertain terms may be emphasized below, any terminology intended to beinterpreted in any restricted manner will be overtly and specificallydefined as such in this Detailed Description section.

FIG. 1 is a block diagram of environment 190 in which the invention maybe practiced. As shown, environment 190 includes base station 100 andwireless devices 197-199. Base station 100 includes antenna 192 and iscoupled to back-haul 194 and to primary power source AC over line 196.Base station 100 and wireless devices 197-199 are configured towirelessly communicate with each other.

Base station 100 may include virtually any device for facilitatingwireless network access. For example, base station 100 may be a wirelesstelephony base station, a wireless network access base station, awireless email base station, and/or the like. In one embodiment, basestation 100 is operated by a mobile telephony service provider.Generally, base station 100 is configured to provide a network interfacefor wireless devices 197-199 by providing an interface (via antenna 192)between wireless devices 197-199 and back-haul 194. Base station 100 andwireless devices 197-199 may communicate using any wireless protocol orstandard. These include, for example, Global System for MobileCommunications (GSM), Time Division Multiple Access (TDMA), CodeDivision Multiple Access (CDMA), Orthogonal Frequency Division MultipleAccess (OFDM), General Packet Radio Service (GPRS), Enhanced Data GSMEnvironment (EDGE), Advanced Mobile Phone System (AMPS), WorldwideInteroperability for Microwave Access (WiMAX), Universal MobileTelecommunications System (UMTS), Evolution-Data Optimized (EVDO), LongTerm Evolution (LTE), Ultra Mobile Broadband (UMB), and/or the like.

Back-haul 194 may be any connection that provides a network interfacefor base station 100. For example, back-haul 194 may include one or moreT-1 connections, T-3 connections, OC-3 connections, frame relayconnections, Asynchronous Transfer Mode (ATM) connections, microwaveconnections, Ethernet connections, and/or the like. In addition,back-haul 194 may provide an interface to a telephone switch (e.g., to a5ESS switch or a Private Branch Exchange switch) to a data network(e.g., to a router or network switch), and/or the like.

Base station 100 is also powered from primary power source AC over line196. Primary power source AC may be provided by virtually any powersource. For example, it may be provided by a public utility, from solarpower, from a turbine, from a fuel cell, and/or the like. At times,however, primary power source AC may provide insufficient power for basestation 100. As discussed below, base station 100 also includes backuppower sources.

Wireless devices 197-199 may include virtually any devices forcommunicating over a wireless network. For example, wireless devices197-199 may include mobile telephones (e.g., cellular telephones, GSMtelephones, TDMA telephones, LTE telephones, etc.), wireless datadevices (e.g., Personal Digital Assistants (PDAs), computers, pagers,etc.), and/or the like.

One skilled in the art will appreciate that although illustrated in thecontext of a wireless telecommunications environment, the invention maybe practiced in any environment in which backup power serves acommercial, public, or private operation or system reliant uponelectrical power.

FIG. 2A is a block diagram of base station 200. Base station 200includes power controller 210, rectifier and switch circuit 230, primarypower interface 250, battery circuit 260, generator 270, andcommunications interface 280. Base station 200 may be employed as anembodiment of base station 100 of FIG. 1.

Power controller 210 is configured to control the power systems of basestation 200. As illustrated, power controller 210 is configured toreceive or provide control signals 212 and status signals COM_STAT,RECT_STAT, and BAT_STAT, and to provide output/control signals RECT_CTL,GEN_CTL, and STATUS, as discussed below.

In one embodiment, power controller 210 is configured to selectivelyenable and disable generator 270 and to control the operation ofrectifier and switch circuit 230 based, at least in part, on the variousstatus and control signal inputs. The operation of power controller 210is discussed in further detail with regards to FIG. 3.

Rectifier and switch circuit 230 may include switching devices of anytype (e.g., power field-effect-transistors, power insulated gatebi-polar transistors, relays, etc.) that are configured to selectivelyswitch (e.g., route) power from either primary power interface 250,battery circuit 260, or generator 270 to communications interface 280.FIG. 2B is a block diagram of an example rectifier and switch circuit230. In FIG. 2B, switching devices 231 route power to the communicationsinterface 280 from the primary power interface 250, battery circuit 260,and generator 270. Rectifier and switch circuit 230 may also beconfigured to selectively switch power from either primary powerinterface 250 or generator 270 to battery circuit 260 for providing acharging current. For example, referring again to FIG. 2B, switchingdevices 232 routes power from either the primary power interface or thegenerator to the battery circuit. The switching between communicationsinterface 280, primary power interface 250, battery circuit 260, andgenerator 270 may be controlled via control signal RECT_CTL from powercontroller 210.

In addition, rectifier and switch circuit 230 may also include multiplerectifiers that are each configured to rectify power either from primarypower interface 250 or from generator 270 before providing it either tocommunications interface 280 or to battery circuit 260. For example,referring again to FIG. 2B, a rectifier 233 rectifies power from theprimary power interface and a rectifier 235 rectifies power from thegenerator. Each of the rectifiers in rectifier and switch circuit 230may be controlled via control signal RECT_CTL from power controller 210.

For some common rectifiers, rectification efficiency increases when therectifier is run at higher loads. However, continuous operation ofrectifiers at higher loads may increase operating temperatures and maylead to premature failure of the rectifiers. Accordingly, when basestation 200 is powered from primary power source AC, communicationsinterface 280's power draw may be balanced across each of the rectifiersof rectifier and switch circuit 230 to reduce the load on eachrectifier. However, during a periods of primary power source reducedavailability, the power drawn by communications interface 280 may bebalanced across fewer rectifiers such that efficiency of each operatingrectifier is increased.

Rectifier and switch circuit 230 may also be configured to providestatus signal RECT_STAT to power controller 210 to, for example,indicate the status of rectifiers, the status of switches, the status ofprimary power source AC, the status of generator 270's output, failureconditions (e.g., failure of particular rectifiers, failure ofparticular switches, excessive current draw from communicationsinterface 280, out of range input voltages, etc.), and/or the like.Status signal RECT_STAT may be provided to power controller 210 toenable power controller 210 to adjust the operation of rectifier andswitch circuit 230 or generator 270 based on these and other conditions.

Primary power interface 250 is configured to couple primary power sourceAC to rectifier and switch circuit 230. Primary power interface 250 mayinclude a circuit breaker, line filter, surge protector, power meter,and/or the like. However, in one embodiment, primary power interface 250may simply be a wire segment connecting primary power source AC torectifier and switch circuit 230.

Battery circuit 260 is configured to store power that is provided byprimary power source AC or by generator 270. Battery circuit 260 mayinclude any number of batteries arranged in any combination of seriesconfigurations, parallel configurations, and/or series and parallelconfigurations. In one embodiment, battery circuit 260 includes multiplestrings of serially connected absorbed glass mat lead-acid batteries.However, any suitable type of battery may be employed. Further, batterycircuit 260 is configured to provide status signal BAT_STAT to powercontroller 210. For example, status signal BAT_STAT may be employed toindicate the output voltage of battery circuit 260, a voltage of eachindividual battery, and/or the like. Also, status signal BAT_STAT mayinclude multiple signals and be provided on one or more signal lines.

Power controller 210 may be configured to determine a failure conditionor approximate a charge percentage for battery circuit 260, and/or thelike, from status signal BAT_STAT. While battery circuit 260 isillustrated as being coupled to rectifier and switch circuit 230 bysignals BAT_IN and BAT_OUT, in other embodiments, signals BAT_IN andBAT_OUT may be a single signal.

Generator 270 is configured to generate power under the control of powercontroller 210 for powering communications interface 280 and forcharging battery circuit 260. Generator 270 is further configured toenable and disable power generation based on control signal GEN_CTL. Theoutput of generator 270 is provided to rectifier and switch circuit 230via signal GEN_PWR.

With certain generators, fuel consumption is primarily a function ofrun-time. For these generators, the increase in fuel consumption isrelatively insignificant when the load current is increased.Accordingly, the total power produced from a given amount of fuel isgreater when operating a generator at high loads for short durations ascompared to continuously operating a generator at lower loads. Inaddition, operating a higher output wattage generator may produce agreater the total power output from a given amount of fuel than a loweroutput wattage generator.

Thus, to conserve fuel, generator 270 may be enabled when the charge onbattery circuit 260 is relatively low and disabled when the charge isrelatively high. While running, generator 270 may be employed to powercommunications interface 280 and to charge battery circuit 260. Whilegenerator 270 is stopped, communications interface 280 may be poweredfrom battery circuit 260. In this way, generator 270 produces more powerfor a given amount of fuel. In one embodiment, generator 270 is enabledwhen the voltage of battery circuit 260 represents that less than a 20percent charge remains on battery circuit 260 and is disabled when thevoltage represents that battery circuit 260 has an 82 percent charge.Although, any other suitable percentages, voltages, charge conditions,and/or the like may be employed. Thus, power controller 210 controlsgenerator 270 to operate intermittently, with high load, when the chargeon battery circuit 260 is below a threshold; otherwise, battery circuit260 provides backup power to communications interface 280. Also,generator 270 may be selected such that while powering communicationsinterface 280 and charging battery circuit 260 near a maximum chargerate (e.g., a manufacturer specified maximum rate, a manufacturerspecified recommended rate, an operator specified rate, etc.) generator270 operates at high load. This selection may be based on the DC loadrequirements of communications interface 280, the power available tocharge battery circuit 260, the number of batteries in battery circuit260, the ampere hour ratings of the batteries in battery circuit 260,expected efficiency, anticipated future power requirements, operatingmargins, and/or the like. In one embodiment, the maximum charge rate forbattery circuit 260 is approximately twice the recommended dischargerate for battery circuit 260.

As one example, a 20 kilowatt water cooled Generac generator and a 370ampere hour battery circuit may be employed to power a Nokia UltraSitecommunications interface having 15 to 18 radio units and an additionaltwo rectifiers in the rectifier and switch circuit. In this example,while powering the communications interface, approximately 80 amperesare available to charge and cool the battery circuit. Also, a chargedbattery circuit has approximately 220 ampere hours (after accounting forinternal resistance and other losses) available to power communicationsinterface 280 between charging cycles. Under normal circumstances, 220ampere hours provides 5.5 to 7 hours of power to communicationsinterface 280. After the generator is enabled, it spends approximately 6hours charging the battery circuit, first at a high load, and later at alower load while cooling off.

Such operation may increase the service life and decrease maintenancefor both battery circuit 260 and generator 270. Likewise, such operationmay increase the length of time that communications interface 280 mayoperate from backup power. In one embodiment, a 250 gallon propane tankmay be sufficient to power communications interface 280 for 6 days withintermittent generator operation as compared to 3.5 days with continuousgenerator operation.

Generator 270 may include a gasoline generator, a diesel generator, apropane generator, a natural gas generator, a methanol generator, anethanol generator, and/or the like. Moreover, generator 270 may beeither air-cooled or liquid cooled.

Communications interface 280 is configured to interface (via antenna292) wireless devices to back-haul 294. Communications interface 280typically includes both digital and radio frequency (RF) electronics. Inone embodiment, communications interface 280 includes a RF transceiverand digital control circuitry. However, other components may also beassociated with a transceiver and/or other circuits. Communicationsinterface 280 is powered from rectifier and switch circuit 230 via lineLOAD_PWR and is configured to provide status signal COM_STAT to indicatean operational status such as failure of back-haul 294, the number ofwireless devices associated with base station 200, power consumptiondata, and/or the like.

FIG. 3 is a block diagram of power controller 310. Power controller 310includes processor 314, battery circuit interface 316, generator controlinterface 318, and operation, management, and control (OMC) interface320. Power controller 310 may be employed as an embodiment of powercontroller 210 of FIG. 2A.

As illustrated, processor 314 is configured to control the operations ofthe rectifier and switch circuit (e.g., via control signal RECT_CTL) andthe generator (e.g., via control signal GEN_CTL) and to provide a statussignal to a remote system (e.g., STATUS). In one embodiment, processor314 is configured to selectively enable and disable the generator based,at least in part, on the primary power source status and a batterycircuit status. For example, the generator may be enabled when there isreduced availability of the primary power source and the battery circuitvoltage falls below a threshold value. Likewise, the generator may bedisabled when the primary power source provides sufficient power, whenthe battery circuit voltage is above another threshold value, when thereis a failure of the battery circuit, when an over-current condition isdetected, when a battery circuit temperature is above a threshold value,when there is a failure in the rectifier and switch circuit, whenprocessor 314 is in reset, and/or the like.

In one embodiment, processor 314 detects a failure of the batterycircuit based on a rate of change of the battery circuit output voltageor of the voltages of the individual batteries of the battery circuit.

To determine these and other conditions, processor 314 receives variousstatus signals as illustrated in FIG. 3. For example, signals COM_STATand RECT_STAT may be employed to respectively represent the status ofthe communications interface and of the rectifier and switch circuit.Likewise, signal BAT_SNS may be employed to represent the output voltageof the battery circuit, signals BAT_MON_1 to BAT_MON_N may be employedto represent the voltage across the individual batteries of the batterycircuit, and signal BAT_TEMP may be employed to represent a temperatureof the battery circuit. Also, signal RESET may be employed to resetand/or hold processor 314 in reset. Finally, control signal OVER_CURRENTmay be employed to represent an over-current condition of the batterycircuit, of the rectifier and switch circuit, of the generator, and/orthe like. Likewise, processor 314 may be configured to control therectifier and switch circuit based, at least in part, on theavailability status of the primary power source, as discussed above.

As illustrated, processor 314 is also configured to provide watchdogsignal WD to a watchdog circuit (not shown). The watchdog circuit may bearranged to reset the processor via the RESET signal if, for example,the watchdog signal WD remains unchanged for a predefined duration. Inother embodiments, internal watchdog circuits, and/or the like, may alsobe employed.

Processor 314 is further configured to receive configuration signalCONFIG to represent a hardware configuration, to set various thresholdlevels, and/or the like. Any number of configuration signals may beprovided. In one embodiment, configurations signals are employed torepresent the number and/or types of rectifiers in the rectifier andswitch circuit, the design voltage of the battery circuit, the type ofgenerator, the number of battery strings in the battery circuit, and/orthe like. For example, a configuration signal may be provided toindicate whether the generator is air-cooled so that an air-cooledgenerator may be run for a cooling off period prior to being disabled byprocessor 314. As another example, a configuration signal may beprovided to indicate the load capacity of the rectifiers so thatprocessor 314 may more accurately determine the number of activerectifiers for providing efficient rectification. As yet anotherexample, a configuration signal may be provided to indicate the designvoltage of the battery circuit so that processor 314 may more accuratelyestimate the charge on the battery circuit from the battery circuitoutput voltage.

Configuration signal CONFIG may be provided from a switch (e.g., a DIPswitch), from pull-up resistors, from pull-down resistors, from jumpers,and/or the like. Alternatively, similar configuration information may beread by processor 314 from a memory or be received from anotherprocessor.

Processor 314 may be a microprocessor, a microcontroller, a digitalsignal processor (DSP), and/or the like. However, in other embodiments,digital logic, analog logic, combinations of digital logic and analoglogic, and/or the like may also be employed instead of a processor. Forexample, such embodiments may be implemented in a field-programmablegate array (FPGA), in an application-specific integrated circuit (ASIC),in other programmable logic devices (PLDs), and/or the like.

Battery circuit interface 316 is configured to interface processor 314to a battery circuit. For example, battery circuit interface 316receives signal BAT_STAT from the battery circuit and provides discretesignals to processor 314. For example, signal BAT_STAT may be amultiplexed signal or may be provided on multiple signal lines. In oneembodiment, battery circuit interface 316 includes an array of analog todigital converters (ADCs) that are configured to digitize each ofsignals BAT_SNS, BAT_MON_1 to BAT_MON_N, and BAT_TEMP for processor 314.However, multiplexers, drivers, buffers, logic gates, analog circuits,and/or the like may also be suitably employed.

Generator control interface 318 is configured to interface processor 314to a generator such as generator 270 of FIG. 2A. In one embodiment,generator control interface 318 includes a relay, a level-shifter, adriver, a buffer, an inverter, logic gates, and/or the like that isconfigured to provide control signal GEN_CTL based, at least in part, onthe output of processor 314. Also, generator control interface 318and/or processor 314 may be configured such that a failure of eithergenerator control interface 318 or processor 314 results in thegenerator being enabled. In this way, a failure of processor 314 and/orgenerator control interface 318 is less likely to cause a powerinterruption at the communications interface.

OMC interface 320 is configured to interface processor 314 to a remotesystem and to provide operational data regarding the base station and/orthe base station power system to the remote system. OMC interface 320may include drivers, buffers, inverters, logic gates, network interfaceunits, multiplexers, and/or the like. Likewise, OMC interface 320 may beconfigured to multiplex the STATUS signal onto the back-haul or mayprovide the STATUS signal as a discrete signal.

FIG. 4 is a schematic diagram of battery circuit 460. Battery circuit460 includes batteries 462, jumpers 464, current limiting resistors 466,and opto-isolator circuits 468. Battery circuit 460 may be employed asan embodiment of battery circuit 260 of FIG. 2A.

As illustrated, battery circuit 460 is configured as a negative 48-voltbattery circuit having one string of serially connected absorbed glassmat lead-acid batteries. In this embodiment, batteries 462 are seriallyconnected by jumpers 464 to form a single battery string. However, otherbattery circuits may be configured with any number of batteries and anynumber of battery strings and may provide any positive or negativeoutput voltage. In addition, battery circuit 460 includes opto-isolatorcircuits 468 to sense the voltage across each of the batteries andassociated jumpers. Current limiting resistors 466 are also included tolimit the current to opto-isolator circuits 468. By couplingopto-isolator circuits 468 across both the battery and the associatedjumper, the effects of loose or corroded connections may be included inthe opto-isolator circuit output and may be detected by the powercontroller.

In other embodiments, other isolated or non-isolated sense circuits maybe employed instead of opto-isolator circuits 468. For example, ADCs,sense resistors, and/or the like may be employed.

FIG. 5 is a schematic diagram of opto-isolator circuit 568.Opto-isolator circuit 568 includes diode D1, transistor Q1, and resistorR1. Opto-isolator circuit 568 may be employed as embodiments ofopto-isolator circuits 468 of FIG. 4.

Opto-isolator circuit 568 is configured to provide an output signal thatis based on the voltage applied across diode D1. In operation, thevoltage across diode D1 causes current flow through diode D1 and causesdiode D1 to provide an emitted light with an intensity that is relatedto the magnitude of the current flow. The emitted light is received bytransistor Q1 to provide an output signal. Resistor R1 biases transistorQ1 and may be of any suitable value.

FIG. 6 is a logical flow diagram of process 600 for conserving power ina wireless communications system. For clarity, process 600 is describedbelow as being performed by base station 200 of FIG. 2A. However,process 600 may also be performed by processor 314 of FIG. 3 and may bestored in non-volatile memory. Process 600 may also be performed byother processors, by other components, or in other systems, whether ornot such processors, components, or systems are described herein.

Flowing from a start block, processing begins at step 610 where powercontroller 210 disables generator 270. For example, power controller 210may disable generator 270 to conserve fuel while primary power source ACprovides power to primary power interface 280. At step 620, primarypower interface 280 receives power from primary power source AC. At step630, rectifier and switch circuit 230 employs a first number ofrectifiers to rectify the received power. For example, to decrease theoperating temperature of the operating rectifiers, the first number ofrectifiers may include all or almost all of the rectifiers in rectifierand switch circuit 230. In one embodiment, base station 200 may employthe rectified power to power communications interface 280 or to chargebattery circuit 260.

At decision block 640, power controller 210 determines whether powerfrom primary power source AC is available. Power controller 210 mayperform this determination based on status signal RECT_STAT, based on astatus signal from primary power interface 250, and/or the like. Ifpower controller 210 does detect availability of power from primarypower source, it returns processing to step 620. Otherwise, powercontroller 210 continues processing at decision block 650.

At decision block 650, power controller 210 determines if the batterycharge is under a lower threshold. For example, power controller 210 mayestimate battery circuit 260's remaining charge based on the batterycircuit 260's output voltage. If this remaining charge is not under thelower threshold, power controller 210 returns processing to decisionblock 640. Otherwise, power controller 210 continues to step 660.

Power controller 210 enables power generation at step 660, for example,by starting generator 270. After power controller 210 enable powergeneration, processing flows to step 670 where rectifier and switchcircuit 230 employs a second number of rectifiers to rectify thegenerated power. In one embodiment, the second number of rectifiers isless than the first number of rectifiers such that each of the operatingrectifiers operates at a higher load and with higher efficiency. Fromstep 670, processing flows to decision block 680.

At decision block 680, power controller 210 determines if the batterycharge is above an upper threshold. For example, power controller 210may estimate battery circuit 260's remaining charge based on the batterycircuit 260's output voltage. If the remaining charge on battery circuit260 is not above the upper threshold, power controller 210 returnsprocessing to decision block 640. Otherwise, power controller 210continues processing at step 690 where power controller 210 disablesgenerator 270. From step 690, power controller 210 returns processing todecision block 640.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the term “connected,”“coupled,” or any variant thereof means any connection or coupling,either direct or indirect, between two or more elements; the coupling ofconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, shall referto this application as a whole and not to any particular portions ofthis application. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number, respectively. The word “or,” in reference toa list of two or more items, covers all of the following interpretationsof the word: any of the items in the list, all of the items in the list,and any combination of the items in the list.

The above detailed description of embodiments of the system is notintended to be exhaustive or to limit the system to the precise formdisclosed above. While specific embodiments of, and examples for, thesystem are described above for illustrative purposes, various equivalentmodifications are possible within the scope of the system, as thoseskilled in the relevant art will recognize. For example, while processesor blocks are presented in a given order, alternative embodiments mayperform routines having steps, or employ systems having blocks, in adifferent order, and some processes or blocks may be deleted, moved,added, subdivided, combined, and/or modified to provide alternative orsubcombinations. Each of these processes or blocks may be implemented ina variety of different ways. Also, while processes or blocks are attimes shown as being performed in series, these processes or blocks mayinstead be performed in parallel, or may be performed at differenttimes. Further, any specific numbers noted herein are only examples:alternative implementations may employ differing values or ranges.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

I claim:
 1. A system for controlling power generation, comprising: acommunications systems base station, including: a communicationsinterface configured to communicatively couple a wireless interface to aback-haul; a switch circuit that is configured to selectively switchpower between multiple power sources and from the multiple power sourcesto the communications interface, wherein the multiple power sources,include: a primary power interface configured to provide power from aprimary power source to the communications interface; a battery circuitinterface configured to provide power to a battery circuit and toreceive power from the battery circuit; and a generator interfaceconfigured to provide power from a generator to the communicationsinterface, to the battery circuit interface, or both; and a powercontroller that is configured to enable the generator when reducedavailability of the primary power source is detected and a sensedvoltage of the battery circuit is below a first threshold, and that isconfigured to disable the generator when reduced availability of theprimary power source is not detected or when the sensed voltage of thebattery circuit is above a second threshold.
 2. The system of claim 1,wherein the switch circuit includes multiple rectifiers each configuredto selectively rectify power from the primary power interface, from thegenerator, or both, and wherein the power controller is furtherconfigured to individually enable and disable each of the multiplerectifiers based, at least in part, on an availability status of theprimary power source to control the switching of the switch circuit andto enable and disable the generator based, at least in part, on anoperational status of the back-haul.
 3. The system of claim 1, whereinthe power controller is further configured to enable the generator if asensed voltage of the battery circuit represents that the batterycircuit has less than a first threshold charge, and to disable thegenerator if the sensed voltage of the battery circuit represents thatthe battery circuit has more than a second threshold charge, and whereinthe power controller further includes a watchdog circuit, and whereinthe power controller is further configured to enable or disable thegenerator based, in part, on an output of the watchdog circuit.
 4. Thesystem of claim 1, wherein the battery circuit includes: a first batteryhaving at least a first terminal and a second terminal; a second batteryhaving at least a first terminal and a second terminal; a first jumperconfigured to connect the second terminal of the first battery to thefirst terminal of the second battery; and an isolator circuit configuredto sense a voltage potential between the second terminal of the firstbattery and the second terminal of the second battery, and wherein thepower controller is further configured to detect a battery circuitfailure based, at least in part, on a rate of change of the sensedvoltage.
 5. The system of claim 1, wherein the power controller isfurther configured to enable the generator if a sensed voltage of thebattery circuit represents that the battery circuit has less than afirst threshold charge, and to disable the generator if the sensedvoltage of the battery circuit represents that the battery circuit hasmore than a second threshold charge, wherein the power controllerfurther includes: a watchdog circuit, and wherein the power controlleris further configured to enable or disable the generator based, in part,on an output of the watchdog circuit, and wherein the battery circuitincludes: a first battery having at least a first terminal and a secondterminal; a second battery having at least a first terminal and a secondterminal; a first jumper configured to connect the second terminal ofthe first battery to the first terminal of the second battery; and anisolator circuit configured to sense a voltage potential between thesecond terminal of the first battery and the second terminal of thesecond battery, and wherein the power controller is further configuredto detect a battery circuit failure based, at least in part, on a rateof change of the sensed voltage.
 6. The system of claim 1, wherein thepower controller is further configured to enable the generator if asensed voltage of the battery circuit represents that the batterycircuit has less than a first threshold charge, and to disable thegenerator if the sensed voltage of the battery circuit represents thatthe battery circuit has more than a second threshold charge.
 7. Thesystem of claim 1, wherein the primary power source is alternatingcurrent (AC) power provided by an electrical utility, wherein thegenerator is a backup generator is powered by gasoline, diesel, propane,natural gas, methanol, or ethanol.
 8. A system for controlling generatedpower in a wireless telecommunications site, the system comprising: apower controller to be coupled to: a communications interface, which iscoupled to a wireless interface and a telecommunications back-haul, aprimary power source, a back-up generator; and a battery circuit,wherein the primary power source, the back-up generator, and the batterycircuit are configured to selectively provide power to thecommunications interface; and wherein the power controller is configuredto intermittently operate the back-up generator based, at least in part,on a charge level from the battery circuit, and wherein during reducedavailability of the primary power source, operation of thecommunications interface is enabled by consumption of at least percentless fuel than required by another system having a back-up generatorthat is operated continuously during the reduced availability of theprimary power source.
 9. The system of claim 8, further comprisingmultiple rectifiers each configured to selectively rectify power fromthe primary power source and the back-up generator, and wherein thepower controller is further configured to individually enable anddisable each of the multiple rectifiers based, at least in part, on anavailability status of the primary power source to enable and disablethe generator based, at least in part, on an operational status of theback-haul.
 10. The system of claim 8, wherein the power controller isfurther configured to enable the generator if a sensed voltage from thebattery circuit is less than a first charge threshold, and to disablethe generator if the sensed voltage from the battery circuit is morethan a second charge threshold, wherein the power controller furtherincludes a watchdog circuit, and wherein the power controller is furtherconfigured to enable or disable the generator based, in part, on anoutput of the watchdog circuit.
 11. The system of claim 8, wherein thepower controller is further configured to enable the generator if asensed voltage from the battery circuit is less than a first chargethreshold, and to disable the generator if the sensed voltage from thebattery circuit is more than a second charge threshold, wherein thepower controller further includes: a watchdog circuit, and wherein thepower controller is further configured to enable or disable thegenerator based, in part, on an output of the watchdog circuit, andwherein the battery circuit includes: a first battery having at least afirst terminal and a second terminal; a second battery having at least afirst terminal and a second terminal; a first jumper configured toconnect the second terminal of the first battery to the first terminalof the second battery; and an isolator circuit configured to sense avoltage potential between the second terminal of the first battery andthe second terminal of the second battery, and wherein the powercontroller is further configured to detect a battery circuit failurebased, at least in part, on a rate of change of the sensed voltage. 12.The system of claim 8 wherein the power controller is further configuredto enable the generator if a sensed voltage from the battery circuit isless than a first charge threshold, and to disable the generator if thesensed voltage from the battery circuit is more than a second chargethreshold.
 13. The system of claim 8, wherein the power controllerfurther includes: a watchdog circuit, and wherein the power controlleris further configured to enable or disable the generator based, in part,on an output of the watchdog circuit, and wherein the battery circuitincludes: a first battery having at least a first terminal and a secondterminal; a second battery having at least a first terminal and a secondterminal; a first jumper configured to connect the second terminal ofthe first battery to the first terminal of the second battery; and anisolator circuit configured to sense a voltage potential between thesecond terminal of the first battery and the second terminal of thesecond battery, and wherein the power controller is further configuredto detect a battery circuit failure based, at least in part, on a rateof change of the sensed voltage.
 14. The system of claim 8, wherein thebattery circuit includes: a first battery having at least a firstterminal and a second terminal; a second battery having at least a firstterminal and a second terminal; a first jumper configured to connect thesecond terminal of the first battery to the first terminal of the secondbattery; and an isolator circuit configured to sense a voltage potentialbetween the second terminal of the first battery and the second terminalof the second battery, and wherein the power controller is furtherconfigured to detect a battery circuit failure based, at least in part,on a rate of change of the sensed voltage.
 15. The system of claim 8,wherein the primary power source is alternating current (AC) powerprovided by an electrical utility, wherein the back-up generator ispowered by gasoline, diesel, propane, natural gas, methanol, or ethanol.16. A system for controlling generated power for a wirelesstelecommunications transceiver, the system comprising: a powercontroller to be coupled to: a communications interface, which iscoupled to a wireless interface, a primary power source, a generator;and a battery circuit, wherein the primary power source, the generator,and the battery circuit are configured to selectively provide power tothe communications interface; and wherein the power controller isconfigured to intermittently operate the back-up generator based, atleast in part, on a charge level from the battery circuit, and whereinduring reduced availability of the primary power source, operation ofthe communications interface is enabled by consumption of at least aselected percent less fuel than required by another system having agenerator that is operated continuously during the reduced availabilityof the primary power source.
 17. The system of claim 16, furthercomprising multiple rectifiers each configured to selectively rectifypower from the primary power source and the generator, and wherein thepower controller is further configured to individually enable anddisable each of the multiple rectifiers based, at least in part, on anavailability status of the primary power source to enable and disablethe generator based, at least in part, on an operational status of aback-haul connected to the communications interface.
 18. The system ofclaim 16, wherein the power controller is further configured to enablethe generator if a sensed voltage from the battery circuit is less thana first charge threshold, and to disable the generator if the sensedvoltage from the battery circuit is more than a second charge threshold,wherein the power controller further includes a circuit, and wherein thepower controller is further configured to enable or disable thegenerator based, in part, on an output of the circuit.
 19. The system ofclaim 16, wherein the primary power source is AC power provided by anelectrical utility, wherein the generator is powered by gasoline,diesel, propane, natural gas, methanol, or ethanol.
 20. The system ofclaim 16, wherein the power controller is further configured to enablethe generator if a sensed voltage from the battery circuit is less thana first charge threshold, and to disable the generator if the sensedvoltage from the battery circuit is more than a second charge threshold.